Question

A ray of light is incident at an angle of ${50}^0$. Then the ray and the mirror are both rotated clockwise by ${10}^0\text{and}{15}^0$ respectively. The angle turned by the reflected ray is

• A. ${10}^0$
• B. ${20}^0$
• C. ${30}^0$
• D. ${40}^0$

Answer 1

Answer: (A)

${10}^0$

If a plane mirror is rotated by an angle $\theta$, then the angle of reflection is shifted by the angle $2\theta$.

Given, the mirror is rotated by an angle ${15}^{\circ }$ and the incident ray is shifted by ${10}^{\circ }$ in the same direction.

So, the relative shift I the angle $=\left({15}^{\circ }-{10}^{\circ }\right)=5^{\circ }$

So, the shift in the angle of reflection is ${10}^{\circ }$